Mass spectrometric identification of cosmic-ray-produced neon in terrestrial rocks with multiple neon components
Mass spectrometric identification of cosmic-ray-produced neon in terrestrial rocks with multiple neon components
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DOI：
10.1016/0012-821x(93)90159-7
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发表时间：
1993-07
影响因子：
5.3
通讯作者：
S. Niedermann;T. Graf;K. Marti
中科院分区：
文献类型：
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作者：
S. Niedermann;T. Graf;K. Marti
对陆地岩石中宇宙射线产生的核素的研究有望提供重要的地貌和冰川学信息，如地表暴露年龄、侵蚀速度和冰川覆盖范围。在稳定的核素21Ne的情况下，宇宙射线产生的成分可能只代表几个成分中的一个，基于三同位素关联的成分解析是必不可少的。我们开发了分析技术，可以对所有干扰离子进行准确的校正。我们表明(对于我们的修正的Nier源)，基于恒电荷态比的双电荷物种的修正并不令人满意。改进后的技术允许对21Ne的~lt；106个原子进行同位素研究。硅层裂比(22Ne/21Ne)是用与Allan Hills砂岩分离的石英标定的，其值为1.243±0.022。对于陆地石英样品，这一比例预计基本上是恒定的，在成分分辨率中应该是有用的。Ne在温度升高时的逐步释放表明，宇宙射线产生的Ne是在相当低的温度下从石英中释放出来的。由此可以估算出Ne在石英中扩散的活化能(90±10kJ/mol)。
Studies of cosmic-ray-produced nuclides in terrestrial rocks are expected to provide important geomorphological and glaciological information, such as surface exposure ages, erosion rates and extent of glacial cover. In the case of the stable nuclide21Ne, the cosmic-ray-produced component may represent but one of several components, and a component resolution based on three-isotope correlations is essential. We developed analytical techniques which permit accurate corrections for all interfering ions. We show (for our modified Nier source) that corrections for doubly charged species based on constant charge state ratios are not satisfactory. The improved techniques permit isotopic studies of < 106atoms of21Ne. The spallation ratio(22Ne/21Ne)cfrom Si was calibrated using a quartz separate from an Allan Hills sandstone and yields a value of1.243 ± 0.022. This ratio is expected to be essentially constant for terrestrial quartz samples and should be useful in component resolutions. The stepwise release of Ne at increasing temperatures shows that cosmic-ray-produced Ne is released from quartz at rather low temperatures. This permits an estimate of the activation energy for Ne diffusion in quartz (90 ± 10 kJ/mol).